There is often the need to fold a flexible sheet of material. For example, millions of pieces of paper are folded each workday so that the paper is folded neatly and can be completely inserted into a standard sized envelope smaller than the piece of paper for mailing or for any of a number of other reasons. For some flexible sheets of material, such as paper, it is commonplace for the folding operation to be performed entirely manually. However, particularly when the sheet is paper or of similar thickness to paper, there is the danger of cutting oneself during the entirely manual folding process.
Partly to address the issue of paper-cuts and partly to increase the speed with which large amounts of folding can be accomplished, automatic folding devices, such as the ones described in U.S. Pat. Nos. 4,391,596; 5,094,658; 5,374,233; 5,876,320; 6,210,309 and 6,852,073, were developed. However, such automatic folding devices are complicated, having several moving parts, rollers, cylinders and/or plowshares. Typically, the complexity results in more opportunities for parts of the folding device to break or malfunction, leading to a system failure. Further, the complexity results in a device that is expensive to make. Even further, such folding devices operate on electrical power, making operating the devices an additional electrical expense when energy costs are high, and making operating the devices an impossibility when the power is out.